Biochemical analysis revealed markedly elevated parathyroid hormone (192.5 pg/mL; normal 15-65 pg/mL) with hypocalcaemia (2.0 mmol/L; normal 2.2-2.6 mmol/L) and profound vitamin D deficiency (20 nmol/L; sufficient >50 nmol/L), consistent with secondary hyperparathyroidism. The gene discussed is PTH; the disease is Hypocalcemia.